During an architectural construction process, serial cutouts need to be fabricated by construction workers into a number of adjacent assembled I-joists to provide spacing and support for piping, tubing, cabling and the like across the I-joists' web portions. In particular, wooden hoists are assembled in architectural constructions in large numbers with small spacing, which requires a multitude of measurement operations and lengthy preparation. The use of a hole cutting apparatus such as the one described in the cross referenced patent, require merely a central reference point at which a pilot drill of the hole cutting apparatus is centered at the begin of the cutting operation. With conventional laser levels well known in the construction business, the marking of all the individual reference points is difficult since the laser beam may propagate only beneath or above the I-joists. Therefore, there exists a need for a specialized laser marking device for serially fabricating cutouts into adjacent assembled I-joists. The present invention addresses this need.